Adverbs are, basically, words that end in -ly. Not only do adverbs describe verbs, adjectives, and other adverbs, they answer questions in the how, when, and where category. To have a better understanding of the term, however, you can refer to AVA (Adjectives, Verbs, Adverbs). (Source: Checking Your Grammar and Getting It Right, by Marvin Terban)
Numerous adverbs that describe how could be: quickly, slowly, well, badly, etc.
Adverbs that describe where could be: outside, here, everywhere, near, inside, etc.
Adverbs that describe when could be: daily, today, often, soon, now, tonight, etc.
When an adverb is describing an adjective, it is usually describing it in the how category. Examples could include: fully aware, too short, really important, etc.
Reminder: When trying to become familiar with the way adverbs can be used, consider AVA.